Strip accumulator means



Nov. 23, 1965 A. v. ALEXEFF ETAL 3,219,289

STRIP ACCUMULATOR MEANS Filed Oct. 8, 1962 2 Sheets-Sheet 2 Ah? KQEQV 91 mvamons ALEXANDER v. ALEXEFF How/ 3 R. RICHARDS IIIL N mm.

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United States Patent 3,219,289 STRIP ACCUMULATOR MEANS Alexander V. Alexetf, Cleveland, and Howard R. Richards, Lakewood, Ohio, assignors to Industrial Ovens, Incorporated, Cleveland, Ohio, a corporation of Ohio Filed Oct. 3, 1962, Ser. No. 228,988 4 Claims. (Cl. 242-5501) The present invention relates to strip accumulator means. For purposes of this application strips are to be understood to include webs such as metal sheet, paper, textiles, films and wide tapes and to also include strands and to also include wires, cords, narrow tapes, tubings, and monofilaments, such as nylon, rayon and glass fiber.

In the processing of strip material it is usually necessary to accommodate static or dynamic tension differentials between various sections of the processing line or to accommodate different strip speeds, particularly at the letoff and take-up ends of the equipment.

To this end there are conventionally employed strip accumulator means, capable of storing and letting off lengths of strip material. The accumulator means generally comprise arrays of rolls mounted to be moved away from and toward each other, with the strip festooned along a succession of reaches extending between the arrays. A plurality of rolls are in each array.

In devices known as compensators, material storage may be an incidental feature of accommodation of tension differentials caused by changes in the relative strip speeds between adjacent sections of the line. Frequently compensators employ only a single roll in one of the roll arrays, and in some applications the relative movement required between the arrays becomes excessive so that it is advantageous to save space by festooning the strip back and forth between a plurality of rolls at each array. For purposes of this present application, compensators having a plurality of rolls at each array are regarded as a type of accumulator.

When a tension differential occurs between the infeed and outfeed strip passing through an accumulator, the accumulator is subjected to severe moment imbalances and resulting rocking loads, and correspondingly heavy and costly structure is required to resist these loads. The rocking loads are particularly severe when the infeed of the strip is suddenly braked, or the outfeed is abruptly accelerated.

The present invention contemplates an organization of accumulator elements so that the moment imbalance caused by dynamic (or static) tension differentials between the input and output strip material will be minimized, thereby making it possible to design accumulator structure which is relatively light and inexpensive even at high strip tensions.

The invention greatly minimizes any rocking tendency and therefore provides for smoother operation than prior forms of accumulator apparatus, particularly at high tensions. Only at much greater cost can prior forms of accumulator apparatus be given a comparable smoothness of operation.

In the drawings:

FIGURE 1 is a diagrammatic view of a strip processing line with accumulators positioned therein.

FIGURE 2 is a schematic diagram illustrating a fourreach accumulator configuration characteristic of the prior art.

FIGURE 3 is a view similar to FIGURE 2 illustrating an accumulator configuration embodying the present invention.

FIGURE 4 is a schematic diagram illustrating a sixreach accumulator configuration characteristic of the prior art.

FIGURE 5 is a view similar to FIGURE 4 illustrating 3,219,289 Patented Nov. 23, 1955 an accumulator configuration embodying the present invention.

FIGURE 6 is another view similar to FIGURE 4 illustrating another accumulator configuration embodying the present invention.

FIGURE 7 is a schematic diagram illustrating an eightreach accumulator configuration characteristic of the prior art.

FIGURE 8 is a View similar to FIGURE 7 illustrating an accumulator configuration embodying the present invention.

FIGURE 9 is another view similar to FIGURE 7 illustrating another accumulator configuration embodying the present invention.

Shown diagrammatically in FIGURE 1 is a strip processing line for processing a strip 10, Let-ofi' equipment 11 may be intermittently stopped to change over from one let-off roll to another, while the outfeed side of the accumulator 12 is called upon to constantly supply the strip re to the processing equipment 13. The strip 10 may pass through a compensator 14 to an additional processing section 15 of the processing line, and momentary or extended strip speed differentials may occur between the sections 13 and 15, such differentials being accommodated by the compensator 14. An accumulator 16 is provided between the processing equipment 15 and take-up equipment 17 to accommodate strip speed differentials which may occur as for example upon stopping of the strip 10 at the take-up section 17 in order to change over from one roll to another.

In the following portions of the description, it will be understood that the illustrated accumulators may be substituted for any of the accumulators 12, 14, and 16 shown in FIGURE 1.

In FIGURE 2, a conventional accumulator is shown. Two arrays of rolls are provided with linkage means for allowing the distance between the arrays to vary. It is usual to move the upper array of accumulator rolls and maintain the lower array stationary. But it is understood of course that the opposite arrangement may be used, or even that both arrays may be moved relative to a fixed base. In the particular example shown, the upper array is movable and is guided by the members 25. Means for urging the arrays apart may comprise spring-operated or counterweight-operated linkages but, in more sophisticated forms of apparatus, usually comprise pneumatic or hydraulic linkages which are adapted to increase or decrease the length of the strip material within the accumulator according to some control factor, such as difference in line speeds at the input and output end. In the illustrated example, hydraulic cylinders 27 acting through cables or chains 28 passing over pulleys or sprockets 26 constitute the means urging the arrays apart.

It will be understood that the same or other linkage means for allowing the distance between the roll arrays to vary, and for urging the arrays apart, are provided for all the devices shown in FIGURES 3-9, but are omitted from the drawings for the sake of clarity.

In FIGURE 2, if the strip is feeding from left to right, a sudden acceleration of a drive roll (not shown) on the outfeed side of the accumulator will increase the tension of the outfeed section 2% of the strip 10 so that it is substantially higher than the tension of the infeed section 20a. The difference between the two tensions is taken up by friction losses in the various rolls of the accumulator. Thus, the tension at the reach 24 will be slightly less than that at 2011 and the tensions at the reaches 23, 22, and 21 will each be respectively lower in the order indicated, the tension at the reach 21 being slightly higher than that at the infeed section 20a of the strip.

The result is that the tension in the reaches 23 and 24 will be substantially higher than that in the reaches 21 and 22, imposing a substantial momement imbalance with respect to an imaginary transverse median plane 20c to thereby cause the movable array or arrays of rolls and the carriage or carriages therefor to tend to rock. These rocking loads may be extremely high when the tension differential between 2th: and 20b amounts to hundreds or even thousands of pounds, and correspondingly heavy and costly structure is required to resist them.

In FIGURE 3, an accumulator 30 is shown embodying the broader aspects of the present invention. It the strip is feeding from left to right, a sudden acceleration of a drive roll on the outfeed side of the accumulator will increase the tension of the outfeed section 3% of the strip 10 so that it is substantially higher than the tension of the infeed section 30a. The difference between the two tensions is taken up by friction losses, so that the tension at the reach 34 will be slightly less than that at the outfeed section 39b and the tensions at the reaches 33, 32, and 31 will each be respectively lower in the order indicated, and the tension at the reach 31 will be slightly higher than that at the infeed section 30a of the strip.

The result is that the tension in the reaches 32 and 33 on the one hand and that in the reaches 31 and 34 on the other hand are approximately equal, minimizing the moment imbalance with resect to an imaginary transverse median plane 30c. Accordingly, there are only very small rocking loads which can be resisted by relatively light structure to thereby greatly minimize the weight and cost of the apparatus.

It is to be noted in FIGURE 3 that the configuration is such that more than half of the reversals between the successive reaches 31, 32, 33 and 34 of the strip make a crossover through the imaginary median plane 300. There are three reversals in FIGURE 3 and the cross-over occurs at two of them. This is to be contrasted with the apparatus in FIGURE 2 where there are also three reaches, but the cross-over occurs at only one of them.

FIGURE 4 illustrates a prior art accumulator 40 having six reaches. It will be understood that upon tension difierential between the outfeed section 4% of the strip and the infeed section 40a of the strip, there will be a substantial moment imbalance with respect to an imaginary transverse median plane 400 which must be resisted by elements having high bending strength. The imbalance will be as between the reaches 41-43 on the one hand and the reaches 44-46 on the other hand.

FIGURE illustrates a six-reach configuration provided according to a preferred aspect of the present invention. The accumulator 50 defines reaches 51-56. The moments generated by tension loads in the reaches 52, 53 and 56 with respect to an imaginary transverse median plane 500 are substantially balanced by the moments generated by the reaches 51, 54 and 55, even when there is a substantial tension diflferential between the outfeed section 50b and the infeed section 50a.

The same observations may be made with respect to the accumulator 60 shown in FIGURE 6, which has reaches 61-66. Even when there is substantial tension differential between the outfeed section 6% of the strip and the infeed section 60a of the strip, there is a substantial balancing of the moment loads generated by the reaches 64, 65 and 62 on the one hand and those generated by the reaches 61, 66 and 63 on the other hand, with respect to an imaginary transverse median plane 600.

Thus again, in both the FIGURE 5 and FIGURE 6 forms of apparatus, there are only small rocking loads which can be resisted by relatively light structure to thereby greatly minimize the weight and cost of the apparatus.

It is to be noted in FIGURES 5 and 6 that the configuration is such that more than half of the reversals between the successive reaches 51-56 or 61-66 of the strip make a cross-over through the imaginary transverse median plane 500 or 600. In both FIGURES 5 and 6 there are five reversals. In FIGURE 5, cross-over occurs in three of them. In FIGURE 6, cross-over occurs in four of them.

FIGURE 7 illustrates a prior art accumulator 70 having eight reaches. It will be understood that upon tension diiferential between the outfeed section 70b and the infeed section 79a of the strip, there will be a substantial moment imbalance with respect to the imaginary transverse median plane 70c, which must be resisted by elements having high bending strength. The imbalance will be as between the reaches 71-74 on the one hand and the reaches 75-78 on the other hand.

FIGURE 8 illustrates an eight-reach configuration provided according to a preferred aspect of the invention. The accumulator defines reaches 81-88. The moments generated by tension loads in the reaches 82, 83, 86 and 87 with respect to an imaginary transverse median plane 80c are substantially balanced by the moments generated by the reaches 81, 84, and 88, even when there is a substantial tension differential between the outfeed section 80b and the infeed section 80a.

The same observation may be made with respect to the accumulator 90 shown in FIGURE 9, which has reaches 91-98. Even when there is a substantial tension differential between the outfeed section 9012 and the infeed section 9%, there is a substantial balancing of the moment loads generated by the reaches 92, 97, 94 and 95 on the one hand and the reaches 91, 98, 93 and 96 on the other hand, with respect to an imaginary transverse median plane 900.

Thus once again, in both the FIGURE 8 and FIGURE 9 forms of apparatus, there are only small rocking loads which can be resisted by relatively light structure to thereby greatly minimize the weight and cost of the apparatus.

Again it is to be noted in FIGURES 8 and 9 that the configuration is such that more than half of the reversals between the successive reaches 81-88 or 91-98 of the strip make a cross-over through the imaginary transverse median plane 800 or 900. In both FIGURES 8 and 9 there are seven reversals. occurs in four of them. In FIGURE 9, cross-over occurs in six of them.

Thus in all the embodiments of FIGURES 3, 5, 6, 8, and 9, the strip makes cross-overs through an imaginary transverse median plane at more than half of the reversals between successive reaches. In all the embodiments, the two outermost reaches constitute a pair of immediately successive reaches located on opposite sides of the median plane, and the two next-to-outermost reaches also constitute a pair of immediately successive reaches located on opposite sides of the median plane. The outermost pair and next-to-outermost pair are respectively 31, 32 and 33, 34 in FIGURE 3; 51, 52 and 53, 54 in FIGURE 5; 61, 62 and 65, 66 in FIGURE 6; 81, 82 and 83, 84 in FIGURE 8; 91, 92 and 97, 98 in FIGURE 9.

It is to be noted that in all the illustrated embodiments of the invention, the two innermost as well as the two outermost reaches constitute a pair of immediately successive reaches located on opposite sides of the median plane. The innermost pairs are respectively 33, 34 in FIGURE 3; 55, 56 in FIGURE 5; 63, 64 in FIGURE 6; 87, 88 in FIGURE 8; and 95, 96 in FIGURE 9. This is a preferred feature of the invention since it leads to an approach to ideal balancing of moment loads. However the balancing of the moment loads generated by the innermost reaches is somewhat less important than the balancing of the moment loads generated by the outermost reaches, because of the relatively short moment arms of the innermost reaches, and becomes less and less important as more and more reaches are employed. Accordingly, in its broader but less ideally advantageous aspects, the invention contemplates equipment where the innermost pair or pairs of reaches may not constitute a pair of immediately successive reaches. This may be particularly applicable where there is a high number of reaches, say in excess of six or eight.

In FIGURE 8, cross-over;

In all the illustrated and preferred embodiments of the invention, it is to be noted that any intermediate reaches, when paired according to their respective orders of inwardness and outwardness with respect to the two outermost reaches and the two innermost reaches, also constitute pairs of immediately successive reaches located on opposite sides of the imaginary transverse median plane. Thus, the intermediate reaches 53, 54 of FIG- URE 5 constitute such a pair of immediately successive reaches. So do the reaches 65, 66 of FIGURE 6. Also the reaches 83, 84 of FIGURE 8 constitute such a pair, and the reaches 85, 86 of this same figure. Reaches 97, 98 of FIGURE 9 constitute such a pair, as do also reaches 93, 94 of this same figure.

The above description of the invention should make it apparent that the invention may be embodied in many different specific strip processing applications. Disclosure of the invention will suggest to the art many possibilities for specific installations which are tailored to particular condition and operating requirements. The scope of the invention is, therefore, not limited to details of the embodiments described above but is to be defined by the claims set forth below.

What is claimed is:

1. An accumulator apparatus comprising first and second arrays of rolls, means allowing the distance between said arrays to vary between a minimum spacing and a maximum spacing, means urging said arrays toward said maximum spacing, a strip, first feed means supplying said strip to said rolls at controlled rates, second feed means removing said strip from said rolls at controlled rates, said feed means permitting movement of said strip through said apparatus in only one direction, said movement of said strip being through an imaginary transverse plane which extends through both of said arrays, said strip passing back and forth along a succession of reaches between said arrays and along reversals between immediately successive reaches, said strip being tensioned to urge said arrays toward said minimum spacing, said strip making crossovers through said plane at more than half of said reversals, at least one of said feed means producing feeding rate variations whereby the total length of said strip on said arrays temporarily changes, said feed means cooperating to limit the amount of temporary change of length of said strip on said arrays to less than the distance between said minimum spacing and said maximum spacing times the number of reaches, said strip and apparatus being free of obstructions preventing movement of any portion of said strip through said apparatus.

2. An accumulator apparatus comprising first and second arrays 'of rolls, means allowing the distance between said arrays to vary between a minimum spacing and a maximum spacing, means urging said arrays toward said maximum spacing, a strip, first feed means supplying said strip to said rolls at controlled rates, second feed means removing said strip from said rolls at controlled rates, said feed means permitting movement of said strip through said apparatu in only one direction, said movement of said strip being through an imaginary transverse plane which extends through both of said arrays, said strip passing back and forth along a succession of more than three reaches between said arrays, said strip being tensioned to urge said arrays toward said minimum spacing, said strip making crossovers through said plane, at least the two outermost and the next-to-outermost of said reaches each constituting a pair of immediately successive reaches located on opposite sides of said plane, at least one of said feed means producing feeding rate variations whereby the total length of said strip on said arrays temporarily changes, said feed means cooperating to limit the amount of temporary change of length of said strip on said arrays to less than the distance between said minimum spacing and said maximum spacing 6 times the number of reaches, said strip and apparatus being free of obstructions preventing movement of any portion of said strip through said apparatus.

3. An accumulator apparatus comprising first and second arrays of rolls, means allowing the distance between said arrays to vary between a minimum spacing and a maximum spacing, means urging said arrays toward said maximum spacing, a strip, first feed means supplying said strip to said roll at controlled rates, second feed means removing said strip from said rolls at controlled rates, said feed means permitting movement of said strip through said apparatus in only one direction, said movement of said strip being through an imaginary transverse plane which extends through both of said arrays, said strip passing back and forth along a succession of an even number of reaches between said arrays, said number of reaches being more than three between immediately successive reaches, said strip being tensioned to urge said arrays toward said minimum spacing, the two outermost of said reaches constituting a pair of immediately successive reaches located on opposite sides of said imaginary plane, the two innermost of said reaches constituting a pair of immediately successive reaches located on opposite sides of said imaginary plane, at least one of said feed means producing feeding rate variations whereby the total length of said strip on said arrays temporarily changes, said feed means cooperating to limit the amount of temporary change of length of said strip on said arrays to less than the distance between said minimum spacing and said maximum spacing times the number of reaches, said strip and apparatus being free of obstructions preventing movement of any portion of said strip through said apparatus.

4. An accumulator apparatus comprising first and second arrays of rolls, means allowing the distance between said arrays to vary between a minimum spacing and a maximum spacing, means urging said arrays toward said maximum spacing, a strip, first feed means supplying said strip to said rolls at controlled rates, second feed means removing said strip from said rolls at controlled rates, said feed means permitting movement of said strip through said apparatus in only one direction, said movement of said strip being through an imaginary transverse plane which extends through both of said arrays, said strip passing back and forth along a succession of an even number of reaches between said arrays, said strip being tensioned to urge said arrays toward said minimum spacing, the two outermost of said reaches constituting a pair of immediately successive reaches located on opposite sides of said imaginary plane, the two innermost of said reaches constituting a pair of immediately successive reaches located on opposite sides of said imaginary plane, and any intermediate reaches, when paired according to their respective orders of inwardness and outwardness with respect to said two outermost reaches and said two innermost reaches also constituting pairs of immediately successive reaches located on opposite sides of said imaginary plane, at least one of said feed means producing feeding rate variations whereby the total length of said strip on said arrays temporarily changes, said feed means cooperating to limit the amount of temporary change of length of said strip on said arrays to less than the distance between said minimum spacing and said maximum spacing times the number of reaches, said strip and apparatus being free of obstructions preventing movement of any portion of said strip through said apparatus.

References Cited by the Examiner UNITED STATES PATENTS 615,859 12/1898 Kraber 24247.5 1,730,887 10/1929 Hempel 242-475 MERVIN STEIN, Primary Examiner. 

1. AN ACCUMULATOR APPARATUS COMPRISING FIRST AND SECOND ARRAYS OF ROLLS, MEANS ALLOWING THE DISTANCE BETWEEN SAID ARRAYS TO VARY BETWEEN A MINIMUM SPACING AND A MAXIMUM SPACING, MEANS URGING SAID ARRAYS TOWARD SAID MAXIMUM SPACING, A STRIP, FIRST FEED MEANS SUPPLYING SAID STRIP TO SAID ROLLS AT CONTROLLED RATES, SECOND FEED MEANS REMOVING SAID STRIP FROM SAID ROLLS AT CONTROLLED RATES, SAID FEED MEANS PERMITTING MOVEMENT OF SAID STRIP THROUGH SAID APPARATUS IN ONLY ONE DIRECTION, SAID MOVEMENT OF SAID STRIP BEING THROUGH AN IMAGINARY TRANSVERSE PLANE WHICH EXTENDS THROUGH BOTH OF SAID ARRAYS, SAID STRIP PASSING BACK AND FORTH ALONG A SUCCESSION OF REACHES BETWEEN SAID ARRAYS AND ALONG REVERSALS BETWEEN IMMEDIATELY SUCCESSIVE REACHES, SAID STRIP BEING TENSIONED TO URGE SAID ARRAYS TOWARD SAID MINIMUM SPACING, SAID STRIP MAKING CROSSOVERS THROUGH SAID PLANE AT MORE THAN HALF OIF SAID REVERSALS, AT LEAST ONE OF SAID FEED MEANS PRODUCING FEEDING RATE VARIATIONS WHEREBY THE TOTAL LENGTH OF SAID STRIP ON SAID ARRAY TEMPORARILY CHANGES, SAID FEED MEANS COOPERATING TO LIMIT THE AMOUNT OF TEMPORARY CHANGE OF LENGTH OF SAID STRIP ON SAID ARRAYS TO LESS THAN THE DISTANCE BETWEEN SAID MINIMUM SPACING AND SAID MAXIMUM SPACING TIMES THE NUMBER OF REACHES, SAID STRIP AND APPARATUS BEING FREE OF OBSTRUCTIONS PREVENTING MOVEMENT OF ANY PORTION OF SAID STRIP THROUGH SAID APPARATUS. 